In West Europe and North America daylight time starts on the last Sunday of March and the first Sunday of April respectively and ends on the last Sunday of October. But since Israel Daylight Time is not determined solely by the Gregorian calendar, Windows system clock does not adjust it automatically. It is therefore necessary to do so manually every year, using, e.g., Time Zone Editor.
According to a law issued in 2005 as a compromise between religious and secular citizens, Israel Daylight Time begins on the first Friday after 31 March inclusive and ends on the last Sunday before Yom Kippur in the Hebrew (Jewish) calendar. There are ten possible patterns as follows; when the daylight time starts at 02:00, it becomes 03:00 (i.e., IDT = GMT+03:00), and when it ends at 02:00, it becomes 01:00 (i.e., IST = GMT+02:00):
- from the last Friday of March to the second Sunday of September
- from the last Friday of March to the third Sunday of September
- from the last Friday of March to the fourth Sunday of September
- from the last Friday of March to the first Sunday of October
- from the last Friday of March to the second Sunday of October
- from the first Friday of April to the second Sunday of September
- from the first Friday of April to the third Sunday of September
- from the first Friday of April to the fourth Sunday of September
- from the first Friday of April to the first Sunday of October
- from the first Friday of April to the second Sunday of October
Number of days
- Shortest: 170 days
- Longest: 191 days
Dates
- Earliest beginning: 26 March
- Latest beginning: 1 April
- Earliest end: 8 September
- Latest end: 13 October
- 2009: pattern 3 = from 27 March 2009 (2 Nisan 5769) to 27 September 2009 (9 Tishrey 5770)